Sex role development in children is based on the processes of social learning and cognitive development. According to social learning theory, the development and emergence of sex-typed behaviors and attitudes can be described by the same learning principles used to account for any other aspect of social behavior, generally principles related to reinforcement and imitation. The cognitive developmental approach adds that an important factor in sex role development is children's awareness of their own sex and their understanding that gender is a basically constant physical attribute. This research is about the effects of sex and vicarious reinforcement on imitation in first-grade children. The results indicate that children in pleasant settings observing non-sex-typed tasks with vicarious verbal reinforcement tend to imitate same-sex models. In threatening settings with vicarious verbal punishments between a male controller and a female model, children do not imitate the female since the male has ruled that she was wrong in the task. Further research under progress by the author is about the effect on children's attitudes of reversing the role in sex-stereotyped occupations in children's literature. (Author/DE)